Housing for capacitive pressure sensor

Abstract

A housing for a capacitive pressure sensor generally utilized to measure fluid pressure. A metallic housing for a ceramic diaphragm provides greater flexural strength to compensate for the differences in the thermal expansion and bulk modulus of elasticity of such ceramic diaphragm and metal housing.

I claim: 
     
       1. A housing for a capacitive sensor used in the measurement of pressure in a fluid, which capacitive sensor includes: a flexible ceramic diaphragm including a reference surface, a bottom surface, sidewalls, and a chamfered shoulder between said reference surface and sidewalls, and a pressure chamber open at the bottom surface, the reference surface being deflectable in response to a force acting in said pressure chamber;   a capacitive sensor positioned so that its capacitance is varied as the diaphragm reference surface is deflected;   wherein said housing comprises a lower member and an upper member connected to each other and enclosing the sensor;   said housing lower member defining a recess for receiving the diaphragm sidewalls, and further defining a channel communicating with the diaphragm pressure chamber; and   said housing upper member defines first and second portions of different diameters, and a shoulder between the first and second portions of different diameters, which shoulder abuts the chamfered shoulder of said flexible diaphragm.   
     
     
       2. A housing for a capacitive sensor as claimed in claim 1 wherein said lower member recess includes a face defining a groove to receive a seal means to contact said diaphragm bottom surface and seal said diaphragm pressure chamber. 
     
     
       3. A housing for a capacitive sensor as claimed in claim 2 wherein a loading ring is mounted on said chamfered shoulder and a Belleville spring is provided between said housing shoulder and said loading ring to maintain said diaphragm bottom surface against said seal means. 
     
     
       4. A housing for a capacitive sensor as claimed in claim 1 wherein a loading ring is mounted on said chamfered shoulder and a Belleville spring is provided between said housing shoulder and loading ring. 
     
     
       5. A housing for a capacitive sensor as claimed in claim 1 wherein said shoulder of said upper member is at an angle that is supplementary to said chamfered shoulder to be matable with said chamfered shoulder to maintain said sensor in said lower member recess. 
     
     
       6. A housing for a capacitive sensor as claimed in claim 1 wherein said sensor is of a ceramic material and said housing is of a metal with a different coefficient of expansion and bulk modulus of elasticity than said ceramic sensor retained therein. 
     
     
       7. A housing for a capacitive sensor as claimed in claim 1 wherein said lower member defines a sidewall and seal groove therein to receive a seal means, which seal means contacts said upper member to seal said capacitive sensor.